Seamless trick-mode with decreased latency for live transcode streaming

ABSTRACT

A method for performing trick-mode operations with decreased latency for transcode streaming includes receiving and recording a stream of video data. A single transcoder may transcode the stream of video data and generate output video data in an output buffer following. Segmentation index information may be generated that refers to the output data in the output buffer. Skip-backwards, skip-ahead, and resume requests received from a client device are responded by retrieving transcoded video data from the output buffer or retrieving and transcoding video data from an input storage. A method for performing skip-ahead trick-mode operation with decreased latency may use two transcoders such as two threads of the single transcoder to transcode temporally current content and forward content. The forward content may be associated with a forward time offset with respect to the temporally current content. The transcoded forward content is provided in response to skip-ahead trick mode request.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of priority under 35 U.S.C. §119from U.S. Provisional Patent Application 61/821,633 filed May 9, 2013,which is incorporated herein by reference in its entirety.

TECHNICAL FIELD

The present description relates generally to communications, and moreparticularly, but not exclusively, to seamless trick-mode with decreasedlatency for live transcode streaming.

BACKGROUND

Adaptive Bit-Rate (ABR) streaming is a technique used in streamingmultimedia over communication networks, for example, the Internet. Somevideo streaming technologies may utilize streaming protocols such asReal Time Protocol (RTP) with Real Time Streaming Protocol (RTSP). ABRstreaming technologies are almost exclusively based on Hyper TextTransport Protocol (HTTP) and are designed to work efficiently overlarge networks that support HTTP, such as the Internet. The typical ABRstreaming technique may have a scheme that partitions a video streaminto a sequence of segments with approximately equal durations inpresentation timeline.

An ABR stream may be advertised by a streaming server as having multiplerepresentations or profiles, each with different stream characteristics(e.g., including bit rate, resolution, etc.) that may suit differentnetwork bandwidth availability or other usage parameters. Each segmentof the video stream may have a random access point (e.g., an I-frame) atthe start of the segment. When network bandwidth changes, a streamingclient may have the option of requesting a new segment of a differentprofile of the same content. The requested new segment typicallyrepresents content that is contiguous to the preceding segment and a setof consecutive segments may be presented smoothly. The typical ABRstreaming server may prepare and transcode the multiple representationsor profiles of the streams offline for streams available in the storage,so when client requests different profiles of stream, ABR streamingserver may retrieve the already transcoded video data and transmitaccordingly. However, this requires extra storage with ABR server forthe transcoded multiple profiles of the same stream content; and theoffline transcode does not work with content received from livebroadcast sources. If the transcode can be performed online while livestreaming, server may save significant storage and could offer ABRstreaming service with live broadcast source. When live transcodestreaming is performed, there are some challenges with how trick modefeatures are supported for ABR streaming service. This application willaddress the seamless trick mode support with decreased latency for livetranscode streaming. Some of the technique in this specification mayalso apply to the offline transcode to prepare for trick mode featureswith the ABR streaming service.

BRIEF DESCRIPTION OF THE DRAWINGS

Certain features of the subject technology are set forth in the appendedclaims. However, for purpose of explanation, several embodiments of thesubject technology are set forth in the following figures.

FIGS. 1A and 1B illustrate examples of an ABR server for performingseamless trick-mode operations for transcode streaming and a clientdevice, in accordance with one or more implementations.

FIG. 2A illustrates an example of an ABR server for performing seamlesspause/resume and/or trick-mode operations, in accordance with one ormore implementations.

FIG. 2B illustrates timing diagrams depicting transcoded and input videosegments in existing systems as well as the ABR server of FIG. 2A, inaccordance with one or more implementations.

FIG. 3 illustrates an example of an ABR server for performing seamlessskip-ahead trick-mode with decreased latency for live streamtranscoding, in accordance with one or more implementations.

FIG. 4 illustrates an example of an ABR server for performing seamlesstrick-mode with decreased latency for live transcode streaming, inaccordance with one or more implementations.

FIG. 5 illustrates an example of a method for seamless trick-modeoperations with decreased latency for transcode streaming, in accordancewith one or more implementations.

FIG. 6 illustrates an example of a method of performing seamlesstrick-mode with decreased latency for live transcode streaming in an ABRserver, in accordance with one or more implementations.

DETAILED DESCRIPTION

The detailed description set forth below is intended as a description ofvarious configurations of the subject technology and is not intended torepresent the only configurations in which the subject technology may bepracticed. The appended drawings are incorporated herein and constitutea part of the detailed description. The detailed description includesspecific details for the purpose of providing a thorough understandingof the subject technology. However, it will be clear and apparent tothose skilled in the art that the subject technology is not limited tothe specific details set forth herein and may be practiced using one ormore implementations. In one or more instances, well-known structuresand components are shown in block diagram form in order to avoidobscuring the concepts of the subject technology.

The subject technology includes a number of advantageous features thatcan substantially surpass the existing solutions in terms ofperformance, speed, and user experience. For example, the disclosedsubject matter provides seamless skip-backwards trick-mode, pause andresume and skip-ahead trick-mode with decreased latency for livetranscode streaming of adaptive bit-rate (ABR) content, as described ingreater details herein.

FIGS. 1A and 1B illustrate examples of an ABR server 110 for performingseamless trick-mode operations for transcode streaming and a clientdevice, in accordance with one or more implementations of the subjecttechnology. The ABR server 110 includes a first transcoder 140, a secondtranscoder 142, an input buffer 150, an output buffer 152, a storagedevice 120 (e.g., digital video recorder (DVR), disk drive, flashmemory, dynamic random access memory (DRAM), or other memory), a networkinterface 160, and an antenna 162. The client device 180 includes anantenna 182, a network interface 184, a buffer 185, a decoder 186, and adisplay 188. Examples of the ABR server 110 may include a remote server,a home or enterprise gateway, or a set-top box (STB). Examples of theclient device 180 may include a television set, a computer display, or ahand-held communication device such as a laptop, a tablet, a mobilephone, etc.

In one or more implementations of the subject technology, a singletranscoder such as the second transcoder 142 may receive, from a source(e.g., the storage device 130 or a live source), a stream of video data.The stream of video data may be recorded in an input buffer 150 (e.g., avideo buffer) that can store a predetermined amount of video data (e.g.,equivalent of 30 sec or more of video data). The input buffer 150 maydelay the received stream of video data by a predetermined amount oftime, for example 30 seconds. The stream of video data may be transcodedby the second transcoder 142. The second transcoder 142 may generate atranscoded video stream including multiple transcoded video segmentswith an output segment size (e.g., 2-10 sec). Some segments of thetranscoded video segments may be stored in an output video buffer (e.g.,a video buffer) 152. In response to a skip-backwards request from theclient device 180, skipping backwards may be performed by retrieving,from the output buffer 152, transcoded video data based on segmentrequest information received from the client device 180 if video datacorresponding to the segment request information associated with theskip-backwards request are available from the output buffer 152.Otherwise, recorded video data may be retrieved from a first storage. Insome aspects, the first storage may be the input buffer 150 or may be adifferent storage such as the storage 120. The server 110 may record thestream of video data in parallel both in the input buffer and thestorage 120 if the source is a live source. The first storage (e.g.,storage 120) may be capable of storing more video data than the inputbuffer 150. In one or more aspects, if the source of the video stream isa stored source such as storage 120, the server 110 may respond to theskip-backwards request by retrieving the recorded video data from thestorage 120. The retrieved data from the first storage may be transcodedby the transcoder 142 and provided, via the network interface 160, tothe client 180.

In one or more implementations of the subject technology, the transcodedvideo data may be generated based on segment request informationreceived from the client device 180. In one or more implementations, thesegmentation boundary markers may be inserted in the stream of videodata fed to the transcoder 142. The transcoder 142 may start a randomaccess picture in the stream of video data where a segmentation boundarymarker is encountered. The output video data may be generated by liningup segments of the output video data with input video segments in timedomain. The segmentation index information may be generated based onrandom access pictures.

In one or more implementations of the subject technology, the ABR server110 may be configured to perform a quick (e.g., with decreased latency)skip-ahead trick-mode operation. For example, the first transcoder 140may receive, from the storage device 120, a stream of video data. Thefirst transcoder 140 may transcode the received stream of video data, astemporally current content. Forward content, which is associated with apredetermined forward time offset with respect to the temporally currentcontent, may be retrieved from the storage device 120. The secondtranscoder 142 may transcode the forward content. The transcodedtemporally current content may be provided to the client device 180 viathe network interface 160.

In one or more aspects, a skip-ahead trick-mode request (e.g., for a 30sec skip-ahead), may be received from the client device 180. In responseto the skip-ahead trick-mode request, an output of the second transcoder142 may be provided to the client device 180. Afterwards, the firsttranscoder may be reassigned to transcode a new forward content, whichis associated with the forward time offset with respect to the output ofthe second transcoder.

The client device 180 may receive a manifest file from the ABR server110, which advertises various profiles associated with the data stream(e.g., video stream) transmitted by the ABR server 110. Each profile mayinclude one or more characteristics, including, a bit rate, a framerate, a segment information (e.g., segment size), etc. The client device180, at certain times and based on the condition of the performance ofthe network (e.g., home network), may request a specific advertisedprofile. The ABR server 110 may respond to the request by providingsegments corresponding to the requested profile to the client device180. The client device 180 may receive the transmitted video stream,store a portion of a segment or one or more segments of the video streamin a buffer 185, decode the received video stream using the decoder 186and display the decoded stream on the display device 188.

FIG. 2A illustrates an example of an ABR server 200 for performingseamless pause/resume and/or trick-mode operations, in accordance withone or more implementations of the subject technology. The ABR server200 may include a transcoder 210, a storage device 220, a recordermodule 230, a network interface 250, an antenna 252, a control module260, an input buffer 240, and an output buffer 242. The transcoder 210may be configured by the control module 260 to receive a stream of videodata from the storage device 220 or a live stream from a source externalto the ABR server 200 via input buffer 240. The network interface 250,along with the antenna 252, may perform communications with otherdevices, such as ABR client devices (e.g., 180 of FIG. 1). Thecommunications may include receiving requests for segment correspondingto one or more ABR profiles, requests for resume, skip-backwards,skip-ahead, and other messages or data and transmitting manifest files,and video data in response to various requests from the other devices.Requests for resume, skip-backwards and skip-ahead may be in the form ofrequests for segments. For example, segments representing variouspresentation times of a video stream may be described in a manifest.Alternatively, requests for resume, skip-backwards and skip-ahead may bein the form of explicit requests for those functions. The ABR server 200may transmit video without the use of segments.

The live stream may be recorded by the recorder module 230 in the inputbuffer 240, which can store a predetermined amount of video data (e.g.,equivalent of 30 sec or more of video data). In some aspects, therecorder module 230 may store the live stream in the storage device 220,which may include a DVR, a hard drive, flash memory or other memory thatcan store substantial amount of video data (e.g., one or more videofiles such as movies). At any moment of time, the input buffer 240 mayhold the most recent portion (e.g., the last 30 sec) of the live stream.The transcoder 210 may transcode the received stream of video data andorganize the transcoded stream in segments, each of which has a size(e.g., 2-10 sec). The transcoded segments may be stored in the outputbuffer 242, which can store a limited amount of video data (e.g.,equivalent of 30 sec or more). In some aspects, the recorder module 230may optionally store the data from output buffer into the storage devicefor an extra amount of video dara (e.g., 5 or more minutes) as well whenoutput buffer is full and treat the output storage as a part of outputbuffer. In some aspects, the control module 260 may generatesegmentation index information in an output index buffer, which may be apart of the output buffer 242. The control module 260 may generate thesegmentation index information based on segment boundary informationrecorded in the input buffer 240, recorder 230, storage 220, or inanother storage. At any moment of time, the output buffer 242 may holdthe most recent portion (e.g., the last 30 sec) of the transcoded videodata. The most recent portion of transcoded video data may be organizedinto segments based on the segmentation index information generated bythe index module.

The control module 260 may respond to a skip-backward request, receivedby the network interface 250 from a client device, by retrievingtranscoded video data from the output buffer 242, based on segmentrequest information received from the client device (e.g., 180 of FIG.1B) if video data corresponding the segment request informationassociated with the skip-backwards request are available from the outputbuffer 242. Otherwise, the control module 260 may retrieve the recordedvideo from a first storage that may include the input buffer 240, anddirect the retrieved video data to the transcoder 210 for transcodingand providing to the client device via the network interface 250. In oneor more aspects, if the corresponding video data associated with theskip-backwards request is not available from the input buffer 240, thecontrol module 260 may retrieve the retrieve video data associated withthe skip-backwards request from the storage device 220 and provide theretrieved video data to the transcoder 210 for transcoding and providingto the client device.

In one or more implementations of the subject technology, the controlmodule 260 may respond to a resume request received from the clientdevice 180 by retrieve from the output buffer 242, video data thatcorresponds to a start of a pause period, if the video data is availablefrom the output buffer 242. Otherwise, the control module 260 mayretrieve video data that corresponds to the start of the pause periodfrom the input buffer 240, or the storage 220, and cause the transcoder210 to transcode the retrieved video data that corresponds to the startof the pause period. In one or more implementations of pause/resumefeature, if the source content is from file storage, a non-real-time(NRT) mode transcoder end-to-end flow control may be used to support aseamless pause/resume function. For example, when client device 180pauses, the output buffer 242 will eventually become full, which willback pressure the transcoder to pause. The control module can pausefeeding transcoder with video data when that occurs. When client resumesto request data, the output buffer 242 will resume to be consumed, thetranscoder would resume operation and control module then can resumefeeding data to the transcoder. In one or more implementations if aboveflow-control based method is not used, for example, when the clientdevice 180 pauses, the fullness of the output buffer 242 can keepgrowing beyond the buffer capacity. In this case, an application maystore the output data to a separate storage file (e.g., recorder 230 orstorage 220, or in another storage). When client resumes, the server maycontinue from where it stopped from the output buffer or output storage.In one or more implementations, if the input is live, when outputpauses, unstopped transcoder 210 may drop video when output buffer 242is full. In that scenario, the whole input stream of video data can berecorded to file storage (e.g., recorder 230, storage 220, or anotherstorage) for later resume usage in case pause is longer than the storagecapacity of the input buffer 240. In other words, when the input buffer240 is implemented as a time-shift file, it should support dynamicalgrowing storage size when reaching fullness to tolerate the longduration of downstream pause. The control module 260 may also insert thecorresponding segment boundary information as in-band marker atbeginning of each intended segment of input video data that is fed tothe transcoder during transcoding, wherein the segmentation boundarymarkers are based on the segmentation index data (which is based onrandom access point in the video stream) generated by the recordermodule 230 when receiving video for live source, or based on thesegmentation index data generated by indexing the file storage sourceoffline. The segmentation index information is also generated in anoutput index buffer (e.g., in the output buffer 242) when transcodergenerates the output video data into the output buffer 242. The outputsegmentation index data may be lined up in presentation time domainbased on the method described below.

A skip-ahead trick-mode request may be fulfilled by the ABR server 200if forward data is available. This may be the case if the source of thevideo data is a stored source (e.g., storage device 220). In this case,the control module 260 may retrieve transcoded video data associatedwith the skip-ahead request from the output buffer 242, based on segmentrequest information received from the client device if transcoded videodata associated with the skip-ahead request are available from theoutput buffer 242. Otherwise, the control module 260 may retrieverecorded video data from the input storage (e.g., buffer 240, storage220, or other storage) and cause the transcoder 210 to transcoderetrieved recorded video data. The control module 260 may furtherretrieve the transcoded video segments associated with the skip-aheadrequest if segment information associated with the skip-ahead request isfound from segment boundary information associated with the inputstorage. The segment information associated with the skip-ahead requestmay include a segment identifier advertised to the client device.

FIG. 2B illustrates time diagrams depicting transcoded and input videosegments in existing systems as well as the ABR server of FIG. 2A, inaccordance with one or more implementations. An existing ABR filestreamer may have multiple bit rate profiles from a single portion ofcontent transcoded off-line ahead of time and ready for use as multiplerepresentations for online ABR streaming service later. A drawback ofthe offline transcode scheme is that the supported bit rate profiles maybe pre-determined, limited, and not changeable on the fly, thereforetaking more storage space (e.g., for storing multiple copies of videocontent in different bit rates including the original bit rate). Forexample, in the existing systems, a transcoder may transcode a portionof input video data by providing a portion of transcoded output videodata that may have a certain segment structure, for instance,characteristics such as segment size (e.g., 2-10 sec), as seen indiagram S1. The segmentation of the transcoded output video data may notcorrespond to the segmentation shown in diagram S2 that may correspondto the input stream of video data. This may be problematic whenattending to skip-ahead and skip-backwards requests. For example, whenresponding to a skip-backward request, as shown in diagrams S1 and S2,since the segment boundaries in S1 and S2 are not aligned, theskip-backwards may end up somewhere inside the segment S2-2 of thediagram S2. However, in order to access any frame in segment S2-2 thedecoder portion of the transcoder may have to retrieve the segment fromthe start of the segment S2-2 and decode the input. Similarly, inresponse to a skip-ahead request the skip-ahead video may start at S1-4of output video segment which requires restarting transcoder from thesegment S2-4 of the diagram S2. Again, the transcoder may have toretrieve the entire video data included in the segment S2-4 from thebeginning of the segment S2-4 and decode from the start of the segmentS2-4 until reaching a frame (or picture), from which the transcodedoutput video has to start, and start transcoding from that frame. Thedecoding of the unwanted portion of segment S2-4 takes transcoder timeand may result in latency.

In one or more implementations of the subject technology, to supportlive transcode streaming, a lineup method may line up segments of theoutput video data (e.g., S4) with segments in the input video stream fedto the transcoder (e.g., S3). As a result, the skip-back or forward orrandom access into the video content requested by client may always belined up with the input video stream fed to the transcoder input. Thissaves some of overhead and latency for both profile switching andtrick-mode random access operations. For example, in the case where thesource video data is already segmented, the segment boundary informationmay be recorded in an input index file that can be a part of the inputbuffer 240 or stored elsewhere. The control module 260 may insertsegmentation boundary marker based on random access pictures, which areinserted by the transcoder 210 wherever a segmentation boundary markeris encountered. The segmentation boundary markers may be inserted in thestream of video data fed to the transcoder. When transcoder sees thein-band segmentation marker, it may start a new random access picture inthe transcode output video. And the output buffer indexing wouldgenerate the output segment index information based on the output videorandom access pictures, which are actually lined up with the inputintended segmentation boundaries in presentation time. The disclosedlineup method can help to support trick-mode random access (e.g.,skip-forward and skip-backwards) by reducing latency and overhead, ascompared to the existing methods described above.

FIG. 3 illustrates an example of an ABR server 300 for performingseamless skip-ahead trick-mode with decreased latency for live streamtranscoding, in accordance with one or more implementations. The ABRserver 300 may include first and second transcoders 310 and 312, astorage device 320, an access module 330, output buffers 350 and 352, anetwork interface 360, an antenna 362, and a control module 370. Thenetwork interface 360, along with the antenna 362, may performcommunications with other devices, such as ABR client devices (e.g., 180of FIG. 1). The communications may include receiving requests forskip-ahead and other messages or data and transmitting video data inresponse to various requests from the other devices. In one or moreimplementations, the first and second transcoders 310 and 312 may not betwo separate pieces of hardware and may comprise two threads of a singlephysical transcoder.

The ABR server 300 may be configured to perform a quick (e.g., withdecreased latency) skip-ahead trick-mode operation. In some aspects, thefirst transcoder 310 may receive, from the storage device 320, a streamof video data. The first transcoder 310 may transcode the receivedstream of video data, as temporally current content. The access module330 may provide the second transcoder 312 with forward content, whichmay be associated with a predetermined forward time offset (e.g., 30 secor more) with respect to the temporally current content. The accessmodule 330 may retrieve the forward content from the storage device 320.While the second transcoder 312 is transcoding the forward content, theoutput of the first transcoder 310 can be provided through the outputbuffer 350 to the network interface 360.

When a skip-ahead trick-mode request (e.g., for a 30 sec skip-ahead) isreceived from a client device (e.g., the client device 180 of FIG. 1) bythe network interface 360, the control module 370 is informed of therequest. In response to the request, the control module 370 may invokethe access module 330 to cause the second transcoder 312 to provide theforward content through the output buffer 352 to the network interface360. At this point, the control module 370 may invoke the access module330 to retrieve, from the storage device 320, a new forward content,which is associated with a forward time offset (e.g., 30 sec) withrespect to the output of the second transcoder 312 and provide theretrieved data to the first transcoder 310. At the same time, thecontrol module 370 may reassign the first transcoder 310 to transcodethe new forward content, and the transcoded output of the firsttranscoder 310 is directed to the output buffer 350.

Similarly, in subsequent (e.g., future) skip-ahead trick-mode requests,the first and second transcoders 310 and 312 may take turn intranscoding the future temporally current and forward content, andprovide the transcoded future temporally current and forward content tooutput buffers 350 and 352, respectively. Each of the output buffers 350and 352 may hold up to a predetermined amount of video data (e.g., atleast two segments) while the buffer output is not transmitted, in orderto be prepared for a response to a future request with low latency. Anadvantage of having the output buffers 350 and 352 is that the ABRserver 300 may provide the buffered content right after receiving theskip-ahead request, so that the decoder of the client device can have atleast a first segment of the video data to process in a substantiallyshort time after a skip-ahead request, without waiting for eithertranscoder 310 or 312 to begin transcoding the requested data.Furthermore, having an unselected one of the output buffers 350 and 352be pre-filled with enough data can enable the decoder to start decodingand displaying as soon as the data is transmitted to the receiver. Inone or more implementations, the content of the output buffers 350and/or 352 (e.g., one or two segments) can be transmitted to the clientdevice as quickly as the network can support the transmission, so thatthe client device can begin decoding the video data received in responseto a request (e.g., skip ahead) with minimal latency.

FIG. 4 illustrates an example of an ABR server 400 for performingseamless trick-mode with decreased latency for live transcode streaming,in accordance with one or more implementations. The server 400 mayinclude a processor 410, a storage device 420, a network interface 430,and memory 450, coupled to one another via a bus 440. The processor mayinclude a number of hardware cores that can perform variousfunctionalities, such as transcoding, scaling, and/or other video/audioprocessing operations. The network interface 430 may performcommunications with other devices, such as ABR client devices (e.g., 180of FIG. 1). The communication may include receiving a request for an ABRprofile, requests for pause, resume, skip-backwards, skip-ahead, andother messages or data and transmitting manifest files, and video datain response to various requests from the other devices. The memory 350may include RAM, DRAM, static RAM (SRAM), flash memory, etc. The storagedevice 420 may include a DVR, a disk drive, flash memory, DRAM, or othertypes of memory.

The memory 450 may include a number of buffers such as a buffer 452(e.g., video buffers) and a number of program modules that can beexecuted by the processor 410. The program modules may perform thefunctionalities of the control modules described above with respect toABR servers 200 and 300 of FIGS. 2 and 3, respectively. In one or moreimplementations, the program modules may reside in a storage device suchas storage 420 or may reside in the processor 410.

FIG. 5 illustrates an example of a method 500 for performing seamlesstrick-mode with decreased latency for live transcode streaming in an ABRserver (e.g., 200 of FIG. 2A), in accordance with one or moreimplementations. A stream of video data may be received, from a source(e.g., an external source or 220 of FIG. 2A) (510). The stream of videodata may be recorded (e.g., by using 230 of FIG. 2A), in an input buffer(e.g., 240 of FIG. 2A) (520). The stream of video data may be transcodedby a transcoder (e.g., 210 of FIG. 2A) following the lineup methoddescribed earlier, and output video data may be generated, for example,in an output buffer (e.g., 242 of FIG. 2A) (530). Segmentation indexinformation may be generated that refers to the output video data in theoutput buffer. In some aspects, the segmentation index information maybe generated in an output index buffer (e.g., as a portion of 242 ofFIG. 2A) (540). The segmentation index information associated with theinput video stream may be generated when the input video streamrecorded. A skip-backwards request from the client device may beresponded to (550) by: retrieving transcoded video data (e.g., by 260 ofFIG. 2A) from the output buffer, based on segment request informationreceived from the client device (e.g., 180 of FIG. 1B) if video datacorresponding to the segment request information associated with theskip-backwards request are available from the output buffer. (552);otherwise, retrieving and transcoding recorded video data from the inputstorage (e.g., 240 or 220 of FIG. 2A) (554).

FIG. 6 illustrates an example of a method 600 for performing a seamlessskip-ahead trick-mode with decreased latency for transcode streaming inan ABR server, in accordance with one or more implementations. A streamof video data may be received from a storage device (e.g., 320 of FIG.3) (610). The received stream of video data may be transcoded, astemporally current content, by using a first transcoder (e.g., 310 ofFIG. 3) (620). Forward content, which is associated with a predeterminedforward time offset with respect to the temporally current content, maybe retrieved from the storage device (630). The forward content may betranscoded by using a second transcoder (e.g., 312 of FIG. 3) (640). Inone or more implementations, the first and second transcoders may bethreads of a single transcoder. The transcoded temporally currentcontent may be provided to a client device (e.g., 180 of FIG. 1B) (650).A skip-ahead trick-mode request may be received from the client device(660). The skip-ahead trick-mode request may be responded to byproviding an output of the second transcoder to the client device (670).

Those of skill in the art would appreciate that the various illustrativeblocks, modules, elements, components, and methods described herein maybe implemented as electronic hardware, computer software, orcombinations of both. To illustrate this interchangeability of hardwareand software, various illustrative blocks, modules, elements,components, and methods have been described above generally in terms oftheir functionality. Whether such functionality is implemented ashardware or software depends upon the particular application and designconstraints imposed on the overall system. Skilled artisans mayimplement the described functionality in varying ways for eachparticular application. Various components and blocks may be arrangeddifferently (e.g., arranged in a different order, or partitioned in adifferent way) all without departing from the scope of the subjecttechnology.

As used herein, the phrase “at least one of” preceding a series ofitems, with the term “and” or “or” to separate any of the items,modifies the list as a whole, rather than each member of the list (i.e.,each item). The phrase “at least one of” does not require selection ofat least one of each item listed; rather, the phrase allows a meaningthat includes at least one of any one of the items, and/or at least oneof any combination of the items, and/or at least one of each of theitems. By way of example, the phrases “at least one of A, B, and C” or“at least one of A, B, or C” each refer to only A, only B, or only C;any combination of A, B, and C; and/or at least one of each of A, B, andC.

A phrase such as “an aspect” does not imply that such aspect isessential to the subject technology or that such aspect applies to allconfigurations of the subject technology. A disclosure relating to anaspect may apply to all configurations, or one or more configurations.An aspect may provide one or more examples of the disclosure. A phrasesuch as an “aspect” may refer to one or more aspects and vice versa. Aphrase such as an “embodiment” does not imply that such embodiment isessential to the subject technology or that such embodiment applies toall configurations of the subject technology. A disclosure relating toan embodiment may apply to all embodiments, or one or more embodiments.An embodiment may provide one or more examples of the disclosure. Aphrase such an “embodiment” may refer to one or more embodiments andvice versa. A phrase such as a “configuration” does not imply that suchconfiguration is essential to the subject technology or that suchconfiguration applies to all configurations of the subject technology. Adisclosure relating to a configuration may apply to all configurations,or one or more configurations. A configuration may provide one or moreexamples of the disclosure. A phrase such as a “configuration” may referto one or more configurations and vice versa.

The word “exemplary” is used herein to mean “serving as an example,instance, or illustration.” Any embodiment described herein as“exemplary” or as an “example” is not necessarily to be construed aspreferred or advantageous over other embodiments. Furthermore, to theextent that the term “include,” “have,” or the like is used in thedescription or the claims, such term is intended to be inclusive in amanner similar to the term “comprise” as “comprise” is interpreted whenemployed as a transitional word in a claim.

All structural and functional equivalents to the elements of the variousaspects described throughout this disclosure that are known or latercome to be known to those of ordinary skill in the art are expresslyincorporated herein by reference and are intended to be encompassed bythe claims. Moreover, nothing disclosed herein is intended to bededicated to the public regardless of whether such disclosure isexplicitly recited in the claims. No claim element is to be construedunder the provisions of 35 U.S.C. §112, sixth paragraph, unless theelement is expressly recited using the phrase “means for” or, in thecase of a method claim, the element is recited using the phrase “stepfor.”

The previous description is provided to enable any person skilled in theart to practice the various aspects described herein. Variousmodifications to these aspects will be readily apparent to those skilledin the art, and the generic principles defined herein may be applied toother aspects. Thus, the claims are not intended to be limited to theaspects shown herein, but are to be accorded the full scope consistentwith the language claims, wherein reference to an element in thesingular is not intended to mean “one and only one” unless specificallyso stated, but rather “one or more.” Unless specifically statedotherwise, the term “some” refers to one or more. Pronouns in themasculine (e.g., his) include the feminine and neuter gender (e.g., herand its) and vice versa. Headings and subheadings, if any, are used forconvenience only and do not limit the subject disclosure.

What is claimed is:
 1. A method for performing seamless trick-modeoperations with decreased latency for transcode streaming, the methodcomprising: receiving, from a source, a stream of video data; recordingthe stream of video data in an input buffer; transcoding, by using asingle transcoder, the stream of video data and generating output videodata in an output buffer; generating segmentation index informationreferring to the output video data in the output buffer; and respondingto a skip-backwards request from the client device by: retrievingtranscoded video data from the output buffer, based on segment requestinformation received from the client device if video data correspondingthe segment request information associated with the skip-backwardsrequest are available from the output buffer; otherwise, retrieving andtranscoding recorded video data from a input storage.
 2. The method ofclaim 1, wherein the segment index information is generated in the inputstorage, and the method further comprises generating the segmentationindex information based on segment boundary information recorded in theinput storage, wherein the input storage may comprise the input buffer,wherein the method further comprises recording the stream of video datain the input storage and the input buffer if the source is a livesource, wherein the input storage is capable of storing more video datathan the input buffer, wherein the input storage comprises a storedsource if the source is not a live source.
 3. The method of claim 2,wherein: the segment information received from the client devicecomprises a segment identifier, the method further comprises determiningthat the requested segments associated with the skip-backwards requestare available from the output buffer, and retrieving the recorded videodata from the input storage further comprises finding the segmentinformation received from the client device from segment boundaryinformation stored in the input storage.
 4. The method of claim 2,further comprising: responding to a resume request, wherein respondingto the resume request comprises: retrieving, from the output buffer,video data that corresponds to a start of a pause period, if availablefrom the output buffer, otherwise, retrieving and transcoding video datathat corresponds to the start of the pause period from the inputstorage.
 5. The method of claim 2, further comprising responding to askip-ahead request, wherein responding to the skip-ahead requestcomprises: retrieving transcoded video data associated with theskip-ahead request from the output buffer, based on segment requestinformation received from the client device if transcoded videoassociated with the skip-ahead request are available from the outputbuffer; otherwise, retrieving and transcoding recorded video data fromthe input storage, wherein retrieving the transcoded video segmentsassociated with the skip-ahead request comprises finding segmentinformation associated with the skip-ahead request, wherein the segmentinformation associated with the skip-ahead request is found from segmentboundary information associated with the first storage, and whereinsegment information associated with the skip-ahead request comprises asegment identifier advertised to the client device.
 6. The method ofclaim 1, wherein transcoding the stream of video data comprises:inserting segmentation boundary markers in the stream of video data fedto the transcoder, and starting a random access picture in the stream ofvideo data where a segmentation boundary marker is encountered, andwherein: generating output video data comprises lining up segments ofthe output video data with input video segments in time domain, andgenerating segmentation index information is based on random accesspictures.
 7. A method for decreased latency during a skip-aheadtrick-mode operation, the method comprising: receiving, from a storagedevice, a stream of video data; transcoding, as temporally currentcontent, the received stream of video data by using a first transcoder;retrieving, from the storage device, forward content, which isassociated with a predetermined forward time offset with respect to thetemporally current content; transcoding the forward content by using asecond transcoder; providing the transcoded temporally current contentto a client device; receiving a skip-ahead trick-mode request from theclient device; and responding to the skip-ahead trick-mode request byproviding an output of the second transcoder to the client device. 8.The method of claim 7, further comprising re-assigning the firsttranscoder to transcode a new forward content, which is associated withthe forward time offset with respect to the output of the secondtranscoder.
 9. The method of claim 7, further comprising: buffering anoutput of the first transcoder and the output of the second transcoderbefore being provided to the client device, wherein buffered contentcomprises a predetermined amount of video data; and providing thebuffered content to the client device faster than real time.
 10. Adevice for performing seamless trick-mode operations with decreasedlatency for transcode streaming, the device comprising: an input bufferconfigured to receive, from a source, and record a stream of video datawhile generating intended segment boundary information; a singletranscoder configured to transcode the stream of video data and togenerate output video data in an output buffer; a control moduleconfigured to: generate segmentation index information in an outputindex buffer; and respond to a skip-backwards request from the clientdevice by; retrieving transcoded video data from the output buffer,based on segment request information received from the client device ifvideo data corresponding the segment request information associated withthe skip-backwards request are available from the output buffer;otherwise, retrieving recorded video data from a first storage andcausing a transcoder to transcode the retrieved recorded video data. 11.The device of claim 10, wherein the control module is further configuredto generate the segmentation index information based on segment boundaryinformation recorded in the first storage, wherein the first storagecomprises the input buffer, wherein the stream of video data is recordedin the first storage and the input buffer if the source is a livesource, wherein the first storage is configured to store more video datathan the input buffer, and wherein the first storage comprises a storedsource if the source is not a live source.
 12. The device of claim 11,wherein: the segment information received from the client devicecomprises a segment identifier, the control module is further configuredto: determine that the requested segments associated with theskip-backwards request are available from the output buffer, andretrieve the recorded video data from the first storage.
 13. The deviceof claim 11, wherein the control module is configured to respond to aresume request by: retrieving, from the output buffer, video data thatcorresponds to a start of a pause period, if available from the outputbuffer, otherwise, retrieving video data that corresponds to the startof the pause period from the first storage, and cause the singletranscoder to transcode the retrieved video data that corresponds to thestart of the pause period.
 14. The device of claim 11, wherein thecontrol module is configured to respond to a skip-ahead request by:retrieving transcoded video data associated with the skip-ahead requestfrom the output buffer, based on segment request information receivedfrom the client device if transcoded video associated with theskip-ahead request are available from the output buffer; otherwise,retrieving recorded video data from the first storage and cause thesingle transcoder to transcode retrieved recorded video data, whereinthe control module is further configured to retrieve the transcodedvideo segments associated with the skip-ahead request, and whereinsegment information associated with the skip-ahead request comprises asegment identifier advertised to the client device.
 15. The device ofclaim 10, wherein: the control module is further configured to insertsegmentation boundary markers in the stream of video data fed to thetranscoder, the segmentation boundary markers are according to thegenerated segment boundary information when recorded in the inputbuffer, the single transcoder is configured to start a random accesspicture in the stream of video data where a segmentation boundary markeris encountered, and the control module is further configured to generatesegmentation index information based on random access pictures, and toline up segments of the output video data with input video segments intime domain.
 16. A device for decreased latency during a skip-aheadtrick-mode operation, the device comprising: a storage device configuredto store a stream of video data; a first transcoder configured totranscode, as temporally current content, the received stream of videodata; a control module configured to retrieve, from the storage device,forward content, which is associated with a predetermined forward timeoffset with respect to the temporally current content; a secondtranscoder configured to transcode the retrieved forward content; anetwork interface configured to provide the transcoded temporallycurrent content to a client device; the control module is furtherconfigured to: receive a skip-ahead trick-mode request from the clientdevice; and respond to the skip-ahead trick-mode request by providing anoutput of the second transcoder to the client device.
 17. The device ofclaim 16, wherein the control module is further configured to re-assignthe first transcoder to transcode a new forward content, which isassociated with the forward time offset with respect to the output ofthe second transcoder.
 18. The device of claim 16, further comprising anoutput buffer configured to store an output of the first transcoder andthe output of the second transcoder before being provided to the clientdevice, wherein, the buffered content is provided to the client devicefaster than real time.
 19. A system for performing seamless trick-modeoperations with decreased latency for transcode streaming, the systemcomprising: memory configured to store one or more program modules; oneor more processors coupled to the memory and configured to execute theone or more program modules to: receive, from a source, a stream ofvideo data; record the stream of video data in an input storage;generate segmentation boundary information in the input storage;transcode, by using a single transcoder, the stream of video data andgenerate output video data in an output buffer; generate segmentationindex information that refers to the output video data in t outputbuffer; and respond to a skip-backwards request from the client deviceby: retrieving one transcoded video data from the output buffer, basedon segment request information received from the client device if videodata corresponding the segment request information associated with theskip-backwards request are available from the output buffer; otherwise,retrieving and transcoding recorded video data from a first storage. 20.A system for providing decreased latency during a trick-mode, the systemcomprising: memory configured to store one or more program modules; oneor more processors coupled to the memory and configured to execute theone or more program modules to: receive, from a storage device, a streamof video data; transcode, as temporally current content, the receivedstream of video data by using a first transcoder; retrieve, from thestorage device, forward content, which is associated with apredetermined forward time offset with respect to the temporally currentcontent; transcode the forward content by using a second transcoder;provide the transcoded temporally current content to a client device;receive a skip-ahead trick-mode request from the client device; andrespond to the skip-ahead trick-mode request by providing an output ofthe second transcoder to the client device.